Are Intellectual Property Rights Detrimental to Innovation?

Intellectual property rights are legal constraints that limit entry in industries where incumbents are innovators. The set of legal constraints is the same for all industries, without considering that the externalities created by entry are not necessarily negative for the incumbent or that the incumbent's R&D expenditures can be detrimental to entrants. We show that one unique set of legal rules can foster innovation and increase total R&D expenditures in some industries and be detrimental in others. The model is illustrated by case studies from the information and communication technologies industry (software, hardware, music and videogame industries).